Poly(3,4‐ethylenedioxythiophene) as Electrode Material in Electrochemical Capacitors

We have investigated the conjugated polymer poly(3,4-ethylenedioxythiophene) as electrode material in electrochemical supercapacitor. The conjugated polymer is prepared by chemical polymerization in the form of thin films on nonconducting plastic substrates. One film is electrochemically reduced to the neutral state, while the other is kept in the as-prepared, doped state. The films are thin immersed in a liquid organic electrolyte. In the charged state the supercapacitor cell voltage is 0.8 V and the energy density is measured to 1 to 4 Wh/kg of active electrode material, depending on the current density used during discharge. The power density (delivered energy/discharge time) also depends on the current density and at the highest current densities investigated (1 mA/cm 2 ) it reaches 2.5 kW/kg of active electrode material.